When April Spicer, 42, first adopted El Vez six years ago he was really quiet. The tiny Chihuahua mix spent the first few days in their Prospect Heights apartment cowering, as if scared. But soon, she says “he started to exhibit some unusual behaviors.”

El Vez became aggressive toward other dogs and would howl incessantly when left alone in the apartment. “He always seemed to be in a level of distress,” she recalls.

Spicer tried holistic remedies to soothe the dog, but nothing worked. “When he was in the red zone, you couldn’t distract him,” she says. Finally, four years ago, she turned to Prozac and the dog calmed down.

In 2007, the FDA approved Prozac, the antidepressant oft prescribed to humans, to treat “canine separation anxiety.” Eli Lilly currently sells it for pets under the name Reconcile. It’s one of many pharmaceutical drugs now being prescribed by veterinarians to treat behavior issues like aggression, anxiety, compulsive disorders like tail chasing and even house soiling.

“The stigma about reaching out for help is decreasing, and our pets are benefiting from that just as we are,” says Dr. E’lise Christensen, a Midtown veterinarian specializing in animal behavior.

“[Reconcile] is a very useful drug and can save pet lives,” adds Dr. Nicholas Dodman, the director of the Animal Behavior Clinic at Tufts University. According to the American Veterinary Medical Association, roughly half of the 6 million dogs and cats surrendered to shelters each year are given up because of behavior problems. “It’s very cheap these days,” he notes, and “long-term use is not a problem — no addiction, no withdrawal.”

Chris Vaskas, a 30-year-old from Middle Village, Queens, says Reconcile saved his dog’s life. His 4-year-old pit bull rescue, Ray, was terrified of being alone. His separation anxiety was so extreme that three foster owners had already given up on the dog when Vaskas took him in. “We weren’t able to leave the house,” he recalls. “We didn’t have a life.”

He tried increasing the dog’s exercise and experimented with different training techniques to no avail. Then he took Ray to Christensen.

She prescribed him Reconcile along with trazodone, an antianxiety and antidepressant given to humans. If needed, the dog also takes Acepromazine, a tranquilizer.

Now, says Vaskas, “he’s healthy, he’s active, he’s playful.” But, he says it took many months of monitoring and trial and error to find which drugs and dosages worked for the dog, and it’s an ongoing process. “Prozac’s not a quick fix at all,” he says. “There’s a lot of work put in.”

Still, some vets think pet owners are wrongly looking to meds for an easy solution.

“People want to see drugs with immediate suppression of symptoms,” says Dr. Marcie Fallek, a holistic vet with a practice downtown. “I can rebalance them with natural means, without side effects.”

Rachel Witz’s adopted Chihuahua Rocket is proof. The little dog had severe anxiety and aggression when Witz, an executive assistant who lives on the Upper West Side, took him to Fallek. The vet prescribed more exercise, homeopathics and a grain-free diet of raw meats and vegetables. “We could have taken the [Prozac] route but didn’t,” she says.

Brian Burton, a certified professional dog trainer at Instinct Dog Behavior and Training on the Upper East Side, cautions that it takes more than just a pill to correct behavioral issues. “The medication itself doesn’t fix anything alone,” he says. “It sets the stage for training to work.”

Dogs aren’t the only ones joining Prozac Nation. Dr. Jean Ferreri, 45 and a Manhattan resident, has had her cat, Lorenzo, on Reconcile for two years. “Lorenzo was always unpredictably aggressive,” she says . A veterinarian herself, Ferreri was initially wary of the drug, but now she’s a believer. “It helped so much,” sheenthuses.

Dr. Tracy Sane, veterinarian and owner of Greenwich Village Animal Hospital, also put his own cat, who was cripplingly shy, on Reconcile.

“I wouldn’t hesitate to recommend its use,” he says. “New York is a scary place when you’re 1-foot-tall.”